One of mobile communication system installation schemes is a small-zone system. In the small-zone system, one service area is covered by a plurality of small zones. Here, a zone is a range in which radio waves emitted from an antenna can be received. A small zone is also called a cell.
Each of the plurality of cells is provided with a radio device and an antenna. Moreover, two or more radio devices are connected to an upper controller.
A fixed region is set up as a service range of the service area. Accordingly, there are cases where characteristics are different for each service area.
For example, a service area including a residential district is characterized by high traffic in the time period from evening to night. A service area including a business district is characterized by high traffic in the daytime.
Resources sufficient to handle traffic in the time period during which traffic peaks need to be provided to each service area. This has caused a problem that the resources could be excessive for a time period in which traffic is low.
One example of a system that addresses the problem is described in PTL 1. In a mobile communication system described in PTL 1, resources are shared among different service areas according to changes in traffic with time. In the mobile communication system, the antenna of each cell is selectively connected to one of a plurality of the upper controllers on a sector-by-sector basis according to the amounts of traffic. In that case, each upper controller is connected to antennas of the cells across a plurality of service areas. Therefore, even when there are differences in traffic among the service areas, differences in traffic depending on time among the controllers can be reduced.
In the mobile communication system described in PTL 1, resources of a plurality of the upper controllers can be shared among a plurality of service areas. Accordingly, resources may be provided according to the total amount of traffic in the plurality of service areas, rather than providing resources of the upper controllers according to traffic peak in each service area. Accordingly, sharing the resources among a plurality of service areas having different traffic peak times can reduce the resources that need to be provided in the upper controllers, as compared with providing an upper controller for each service area.